1. Field of the Invention
The present invention relates to a roller guiding apparatus to be incorporated into a machine tool etc.
2. Description of the Related Art
The applicant of the present application previously developed a roller guiding apparatus shown in FIG. 8 to be incorporated into a machine tool. This roller guiding apparatus has a guide rail 3 provided with upper rolling paths 1 in its upper surface and with side rolling paths 2 in its side surfaces, a moving block 8 having an upper portion 4 provided with rolling paths 6 corresponding to the upper rolling paths 1 and side portions 5 extending vertically downward from the upper portion 4 and provided with rolling paths 7 corresponding to the side rolling paths 2, upper rollers 9 retained on the upper portion 4 of the moving block 8 so as to roll along the upper rolling paths 1 of the guide rail 3, and side rollers 10 retained on the side portions 5 of the moving block 8 so as to roll along the side rolling paths 2 of the guide rail 3. The moving block 8 supported by the upper rollers 9 and the side rollers 10 on the guide rail 3 moves along the guide rail 3.
The entire upper surface of the guide rail 3 of the roller guiding apparatus is flat and the upper rolling paths 1 are parallel to the upper surface. The side rolling paths 2 are flat and inclined surfaces which are inclined to the upper surface of the guide rail 3. The rolling paths 6 formed in the upper portion of the moving block 8 so as to correspond to the upper rolling paths 1 of the guide rail 3 are flat surfaces which are parallel to the upper rolling paths 1. The rolling paths 7 formed in the side portions 5 so as to correspond to the side rolling paths 2 of the guide rail 3 are flat and inclined surfaces which are parallel to the side rolling paths 2. The rollers 9 and 10 retained on the upper portion 4 and the side portions 5, respectively, of the moving block 8 are cylindrical rollers.
Generally, a plurality of roller guiding apparatuses, for example, four roller guiding apparatuses, are incorporated into a machine tool to support an object.
In the foregoing known roller guiding apparatus, the cylindrical rollers 9 and 10 retained on the upper portion 4 and the side portions 5, respectively, of the moving block 8 roll along the flat upper rolling paths 1 formed in the upper surface of the guide rail 3 and the flat side rolling paths 2 formed in the side surfaces of the guide rail 3, respectively, as the moving block 8 moves along the guide rail 3.
When a lateral force, i.e., a force acting in a direction perpendicular to the guide rail 3, acts on the moving block 8 due to a positional error in installing the guide rail 3 and the moving block 8 is displaced laterally relative to the guide rail 3, the cylindrical rollers 9 and 10 are tilted. Consequently, end surfaces of the cylindrical rollers 9 and 10 come into irregular contact with side surfaces defining the flat rolling paths 1 and 2 and the cylindrical rollers 9 and 10 are unable to roll smoothly. If the guide rail 3 meanders slightly, the moving block 8 is unable to move smoothly. Thus, this known roller guiding apparatus does not have sufficient ability necessary to deal properly with problems that arise when a lateral force is applied to the moving block 8.
The flat upper rolling paths 1 and the flat side rolling paths 2 of the foregoing roller guiding apparatus are bottom surfaces of grooves. Therefore end surfaces of the cylindrical rollers 9 and 10, and the side surfaces of the grooves defining the flat upper rolling paths 1 and the flat side rolling paths 2 must accurately be formed, which increases the manufacturing cost.
The moving block 8 of the foregoing roller guiding apparatus is formed of steel. Therefore, through holes for receiving the rollers 9 and 10 therein must be formed in the moving block 8 by machining. When forming the through holes by machining, pilot holes are formed in the moving block 8 and then the pilot holes are machined in a desired shape by broaching. Thus, the through holes are formed by several machining steps. The pilot holes must be formed straight with a high machining accuracy.
Accordingly, it is difficult to manufacture this known roller guiding apparatus at high productivity.